Many innovative technologies have been developed around the world to meet its energy demands using renewable and nonrenewable resources. Solar energy is one of the most important emerging renewable energy resources in recent times. This study aims to present the state-of-the-art of parabolic trough solar collector technology with a focus on different thermal performance analysis methods and components used in the fabrication of collector together with different construction materials and their properties. Further, its industrial applications (such as heating, cooling, or concentrating photovoltaics), solar energy conversion processes, and technological advancements in these areas are discussed. Guidelines on commercial software tools used for performance analysis of parabolic trough collectors, and international standards related to performance analysis, quality of materials, and durability of parabolic trough collectors are compiled. Finally, a market overview is presented to show the importance and feasibility of this technology. We believe the compilation of reviews related to the above aspects will further provide impetus for the development of this technology in the near future.
This paper shows novel formulations of nanolubricants added with multi-layer graphene (MLG), multilayer graphene impregnated with copper (MLG-Cu), and multi-layer graphene impregnated with polyaniline (MLG-PANI) for applications in automotive engines. These nanofluids were prepared using commercial motor oil as the base fluid. The tribological properties were measured at 100 °C, and significant reductions were found in the coefficient of friction and wear. The concentrations used were 0.5% and 2% by weight, obtaining reductions in the friction coefficient and wear of up to 43% and 63%, respectively, in the case of motor oil with copper-impregnated graphene. All formulations of MLG, MLG-Cu, and MLG-PANI did not show any sedimentation when dispersed in engine oil, even three months after being produced.
Sustainability and depletion of fossil
fuels have propelled the
use of renewable energy sources to meet energy demands. Solar radiation
is perhaps the most economical and widely available alternative energy
source. Energy in the form of solar radiation can be recovered using
either photovoltaic or thermal processes. Nowadays, both approaches
can only capture a small fraction of the available solar radiation.
In this work, we have addressed the dynamic optimal operation of thermal
solar plants during start-up. During a normal operating day when solar
radiation becomes available, power should be available as soon as
possible to meet consumer demands. One of the major problems related
to thermal solar plants is the lack of power when solar radiation
is off. To overcome this problem, energy storage tanks are considered
in the design of the thermal plant. We assume that a conventional
Rankine cycle can be used for power generation from low-temperature
energy sources. In this work, a dynamic optimization framework is
deployed to identify optimal dynamic start-up policies in thermal
solar plants. Since the dynamic plant model is composed of a set of
partial and differential equations, we have deployed the method of
lines and the direct transcription approach for spatial and time discretization,
respectively. The results indicate that fast optimal control policies
result in power production in a more efficient fashion than simple
heuristic-based start-up policies.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.